1,277 research outputs found

    Symmetric Strategy Improvement

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    Symmetry is inherent in the definition of most of the two-player zero-sum games, including parity, mean-payoff, and discounted-payoff games. It is therefore quite surprising that no symmetric analysis techniques for these games exist. We develop a novel symmetric strategy improvement algorithm where, in each iteration, the strategies of both players are improved simultaneously. We show that symmetric strategy improvement defies Friedmann's traps, which shook the belief in the potential of classic strategy improvement to be polynomial

    Experimental Inoculation of Growing Pigs with U.S. Strains of Swine and Human Hepatitis E Viruses

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    U.S. strains of swine and human hepatitis E viruses (HEV) are closely related genetically. We found that swine and human HEV differ in virulence and both induce subclinical, but morphologically discernable, hepatitis in experimentally infected SPF pigs. Experimental inoculation of pigs with human HEV may provide a useful model to study the pathogenesis of hepatitis E virus infection and test efficacy of human HEV vaccines

    Experimental infection of pigs with the newly identified swine hepatitis E virus (swine HEV), but not with human strains of HEV

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    A novel virus of pigs, swine hepatitis E virus (swine HEV), was recently identified and shown to be antigenically and genetically related to human HEV. In the present study, we attempted to infect specific-pathogen-free (SPF) pigs experimentally with swine HEV or with human strains of HEV. Serum samples collected from naturally infected pigs were used as the source of swine HEV. Pigs inoculated intravenously with serum samples containing swine HEV seroconverted to anti-HEV 4 to 8 weeks postinoculation, and the virus spread to an uninoculated pig. Swine HEV was detected in nasal and rectal swab materials as early as 2 weeks postinoculation and for 4 to 8 weeks thereafter. Viremia appeared 4 to 6 weeks postinoculation and lasted 1 to 3 weeks. The inoculated pigs appeared clinically normal and serum liver enzymes were not significantly elevated. In contrast, pigs were not infected when inoculated intravenously with about 105 monkey infectious doses of one of two human strains of HEV (Sar-55 or Mex-14)

    The impact of intellectual disabilities on elite sports performance

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    Athletes with intellectual disabilities (ID) were re-introduced into the Paralympics in London 2012. As part of this development a classification system had to be established evidencing the impact this impairment has on elite sports performance. This review examines the research behind this issue. Firstly it examines the limited literature comparing the standards reached by top-level athletes with ID with those without disabilities, and then moves on to look at the research demonstrating differences in both the cognitive and physical skills needed for elite performance. The article then reviews the factors that may be implicated to account for this disparity, from a range of perspectives. A case is made for the importance of looking at this area in terms of the potential for the transferability of research findings from this group to talent identification in mainstream athletes and the benefits of integrating neuropsychological concepts and approaches to understanding the cognitive components behind the development of particular skills associated with high-level performance in specific sports

    Dust and gas in luminous infrared galaxies - results from SCUBA observations

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    We present new data taken at 850 μ\mum with SCUBA at the JCMT for a sample of 19 luminous infrared galaxies. Fourteen galaxies were detected. We have used these data, together with fluxes at 25, 60 and 100 μ\mum from IRAS, to model the dust emission. We find that the emission from most galaxies can be described by an optically thin, single temperature dust model with an exponent of the dust extinction coefficient (kλλβk_\lambda \propto \lambda^{-\beta}) of β1.52\beta \simeq 1.5 - 2. A lower β1\beta\simeq 1 is required to model the dust emission from two of the galaxies, Arp 220 and NGC 4418. We discuss various possibilities for this difference and conclude that the most likely is a high dust opacity. In addition, we compare the molecular gas mass derived from the dust emission, MdustM_{dust}, with the molecular gas mass derived from the CO emission, MCOM_{CO}, and find that MCOM_{CO} is on average a factor 3 higher than MdustM_{dust}.Comment: 10 pages, 6 figures, latex, with MN-macros, accepted by MNRAS - revised version (changed flux values for some galaxies

    Modelling of Multi-Agent Systems: Experiences with Membrane Computing and Future Challenges

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    Formal modelling of Multi-Agent Systems (MAS) is a challenging task due to high complexity, interaction, parallelism and continuous change of roles and organisation between agents. In this paper we record our research experience on formal modelling of MAS. We review our research throughout the last decade, by describing the problems we have encountered and the decisions we have made towards resolving them and providing solutions. Much of this work involved membrane computing and classes of P Systems, such as Tissue and Population P Systems, targeted to the modelling of MAS whose dynamic structure is a prominent characteristic. More particularly, social insects (such as colonies of ants, bees, etc.), biology inspired swarms and systems with emergent behaviour are indicative examples for which we developed formal MAS models. Here, we aim to review our work and disseminate our findings to fellow researchers who might face similar challenges and, furthermore, to discuss important issues for advancing research on the application of membrane computing in MAS modelling.Comment: In Proceedings AMCA-POP 2010, arXiv:1008.314

    Local biases drive, but do not determine, the perception of illusory trajectories

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    When a dot moves horizontally across a set of tilted lines of alternating orientations, the dot appears to be moving up and down along its trajectory. This perceptual phenomenon, known as the slalom illusion, reveals a mismatch between the veridical motion signals and the subjective percept of the motion trajectory, which has not been comprehensively explained. In the present study, we investigated the empirical boundaries of the slalom illusion using psychophysical methods. The phenomenon was found to occur both under conditions of smooth pursuit eye movements and constant fixation, and to be consistently amplified by intermittently occluding the dot trajectory. When the motion direction of the dot was not constant, however, the stimulus display did not elicit the expected illusory percept. These findings confirm that a local bias towards perpendicularity at the intersection points between the dot trajectory and the tilted lines cause the illusion, but also highlight that higher-level cortical processes are involved in interpreting and amplifying the biased local motion signals into a global illusion of trajectory perception

    Local biases drive, but do not determine, the perception of illusory trajectories

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    When a dot moves horizontally across a set of tilted lines of alternating orientations, the dot appears to be moving up and down along its trajectory. This perceptual phenomenon, known as the slalom illusion, reveals a mismatch between the veridical motion signals and the subjective percept of the motion trajectory, which has not been comprehensively explained. In the present study, we investigated the empirical boundaries of the slalom illusion using psychophysical methods. The phenomenon was found to occur both under conditions of smooth pursuit eye movements and constant fixation, and to be consistently amplified by intermittently occluding the dot trajectory. When the motion direction of the dot was not constant, however, the stimulus display did not elicit the expected illusory percept. These findings confirm that a local bias towards perpendicularity at the intersection points between the dot trajectory and the tilted lines cause the illusion, but also highlight that higher-level cortical processes are involved in interpreting and amplifying the biased local motion signals into a global illusion of trajectory perception

    Leaf venation, as a resistor, to optimize a switchable IR absorber

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    Leaf vascular patterns are the mechanisms and mechanical support for the transportation of fluidics for photosynthesis and leaf development properties. Vascular hierarchical networks in leaves have far-reaching functions in optimal transport efficiency of functional fluidics. Embedding leaf morphogenesis as a resistor network is significant in the optimization of a translucent thermally functional material. This will enable regulation through pressure equalization by diminishing flow pressure variation. This paper investigates nature’s vasculature networks that exhibit hierarchical branching scaling applied to microfluidics. To enable optimum potential for pressure drop regulation by algorithm design. This code analysis of circuit conduit optimization for transport fluidic flow resistance is validated against CFD simulation, within a closed loop network. The paper will propose this self-optimization, characterization by resistance seeking targeting to determine a microfluidic network as a resistor. To advance a thermally function material as a switchable IR absorber
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